Supercharger



June 6, 1944. H. A. JOHNSON SUPERCHARGER Filed Dec. 2, 1942 2 Sheets-Sheet l Inventor I Howa rd AJohnson,

H i 5 Attcn ney.

June 6, 1944. JOHNSON 2 ,350,616

SUPERCHARGER Filed Dec. 2, 1942 2 Sheets-Sheet 2 I lnventlbr Howard AJohnson,

b JAMA M Hls Attorney.

Patented June 6, 1944 orrica SUPERCHARGEB Howard A. Johnsom Melrose, Masa, assignor to General Electric Company, a corporation of New York 11 Claims.

The present invention relates to compressors and especially to compressors for turbosuperchargers although it is not limited thereto necessarily. The invention has to do particularly with the'stationary part of the compressor, i. e., the casing and diffuser structure.

Compressors of turbosuperchargers are sub- Jected to severe operating conditions due to the high temperatures involved, the high speeds of the rotating parts, and the differences in temprature existing between contiguous parts. Temperatures may m of the order of 400 degrees F., speeds may be of the order of 25,000 R. P. M. and the temperatures of contiguous parts may differ by as much as 400 degrees F. In addition, relatively moving parts must run with close clearances, clearances of the order of .040 to .050 inch, to obtain good efliciencies. This requires that the stationary structure of the compressor must be rigid and well supported so as to maintain the desired clearances and avoid rubbing of relatively moving parts. lAt the same time, the compressor must be relatively light in weight, weight being an important factor in apparatus for use on aircraft.

One object of my invention is to provide an improved construction and arrangement of the stationary structure of a centrifugal compressor which is light in weight, capable of being. manufactured in quantities at low cost and which will fulfill the exacting operating requirements met with in connection with turbosuperchargers.

. A further object of my invention is to provide an improved construction and arrangement whereby the stationary structure can be quickly and easily assembled on and removed from the turbosupercharger as a unit.

Other objects and advantages of rm! invention will be pointed out hereinafter.

For a consideration of what I believe to be novel and my invention, attention is directed to the following specification and the claims appended thereto.

Mounted on one end of shaft 2, is the compressor impeller 3. On the other end of shaft 2 is mounted the bucket wheel (not shown) of the turbosupercharger, as is known. The compressor casing is supported onarms 4 formed integral with bearing housing I, four arms being indicated in the present instance. At 5 are webs fixed to the arms and to the bearing housing for reinforcing and strengthening the arms.

The stationary part of the compressor comprises walls forming an inlet 6, a difiuser' i, an annular discharge scroll 8 and a discharge conduit 9. This stationary structure is attached to arms 4 by tie bolts i0, forming a support for the bearing and the turbine, and it is itself adapted to be at ached to a suitable support by ears H.

Referring now particularly to Figs. 2, 2 and 3. the stationary structure of the compressor comprises a rear scroll section l2, a rear cone section 13, diffuser vanes M, a diffuser vane plat It, a front cone section It and a front scroll section ii. The rear and front scroll sections l2 and I1 are provided with flanges l8 and I9, respectively, which are suitably welded together, "and their walls are shaped as shown clearly in th drawings to define the annular discharge scroll 8 and the discharge conduit 9.

, tition wall 2% provided with side flanges 2d and 25 In the drawings, Fig. 1 is a,sectional view of a centrifugal compressor which forms a part of a turbosupercharger and which has a stationary structure embodying my invention; Fig. 2 is an (see Fig. 3). The side flanges are notched anct shaped to fit together as is shown in Fig. 2 amt when thus assembled define curved diffuser-passages for the flow of fluid. Flanges 24 are suitably welded to wall 2!. Flanges 25 are suitably welded to difiuser plate l5 which is saw tooth shaped as shown in Fig. 2 so that in contour it corresponds with the side contour of assembled iiange 28 which is suitably welded to an axially 7 extending flange 29'on front scroll section ll.

Welded to the walls which define inlet 6 and outlet 9 are suitable flanges 30 and 3|, respectively, provided with openings to receive bolts for at-- tachment to pipe lines.

Mounting ears I I are suitably welded to flanges l8, l9 and scroll section I1 and they are provided with reinforcing webs 32 which are welded to section II, the webs extending radially across section I! down to flange 29. Four mounting. ears H are shown; They are provided with openings 33 to receive bolts for mounting the turbosupercharger on a support. Also they are provided with openings 34 to receive the ends of the rods 35 which support a cooling air baiile plate 36. Attached to scroll section H are additional ears 31, three in the present instance, located between ears I I for additional tie rods 35. Ears 31 ar reinforced by webs 38 which are welded to the ears and to scroll section ll. Welded to flanges 28, 29 in line with the inner ends of webs 32 are spaced lugs 39 in which the ends of the bolts Ill are threaded. At 40 are a number oi reinforcin rods which at one end are welded to diffuser vane plate l and at the other end to scroll section il, being in line with webs 32. In Figs. 2 and 2, 4| indicates the openings in scroll section ll and webs 32 through which the ends of rods extend.

The opening v42 deflned by flange 21 on front cone section I6 is of a diameter larger than the diameterof impeller 3 and such opening is closed by a plate 43 the intermediary of webs 44 which at one end are welded to plate 43 and at the other end are located between collars 46 on the bolts l9 and arms 4, as best shown in Fig. 4. Between flange 21 and the periphery of plate 43 is a suitable packing 45.

One advantage of our invention is the ease and accuracy with which the structure may be assembled. The several parts l2 to ll, inclusive, may be made from sheet steel. All parts are so shaped that they can be readily formed as stampings. In assembling the construction, the rear scroll section l2 and the rear cone section l3 may. be correctly positioned relatively to each other and seam welded together, after which the several diffuser vanes l4 may be spot welded to flange 2|. Next, the diffuser vane plate l5 and the front cone section l9 may be accurately positioned relatively to each other and welded together by seam -welding, for example, and reinforcing rods 40 welded to the diffuser vane plate.- This assembly may then be attached to the assembly comprising rear scroll section l2, rear cone section 13 and the diffuser vanes H by spot welding flanges to vane plate is. There is now left only the front scroll section I1 and it may be readily positioned 'on the assembled construction, flange I! being seam welded to flange I9 and the ends of reinforcing rods 49 which now project through openings 4| welded on the outside. Following this, the lugs H, 31

and 39 and the reinforcing webs 32 and 39 'may be welded into place.

The structure as a whole may be readily. mounted on supporting arms 4 by assembling it over the impeller wheel and positioning the tie bolts l0. 'Iie bolts Il may be attached to lugs 39 before the casing is positioned on the turbosupercharger. It is then merely necessary to passthe tie bolts through the openings in arms 4 and position the nuts on the ends of the tie bolts. To dismantle the construction, it is necessary merely toremove the nuts from bolts III and tie rods whereupon the casing can be removed axially.

It will be noted that the rear cone section 03,

' diffuser vane plate I and the front cone section supported by the bolts l0 through front and rear scroll sections l2 and il. These sections l3, l5 and I6, when assembled with the diffuser vanes I4 and the lugs 39, form. a rigid structure of heavier metal. In the operation of the compressor, it is important to maintain a close clearance between the inner surface of wall 29 and the adjacent edges of the impeller blades. This clearance is defined by the engagement of lugs 39 with the ends of supporting arms 4. Accordingly, the clearance may be adjusted by means of shims located on the bolts l9 between lugs 39 and arms 4. Of the assembled casing structure, only the outer surfaces of lugs 39 require machining. These are machined accurately with respect to the inner surface of wall 29- of the rear cone section so as to make this distance accurate. In other words, the surface of lugs 39 is machined accurately with respect to the inner surface of wall 29 to a dimension such that when the casing is assembled there will obtain a correct clearance between wall 29 and the edges of the impeller vanes. This is the only critical dimension requiring close tolerance. Since there is only one dimension to be machined accurately, there can be no accumulation of tolerances as may be the case where there are several surfaces which are assembled relatively to I .gether. Thus, viewed from one aspect, ears 33,

webs 32 and lugs 39 form in substance rigid supporting arms for the turbosupercharger as a whole, the arms being connected together or reinforced by front scroll section II. Accordingly, when ears 33 are bolted to a main support, the bearing and bearing housing are rigidly fixed in position to carry the overhung compressor impeller and the overhung turbine wheel.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and the invention may be carried outv tached to said rigid structure.

2. In a centrifugal compressor having a rotatins impeller overhung on a shaft end, a fabricat-' ,ed unitary rigid casing structure for the compressor comprising spaced walls which define a diffuser surrounding the impeller, one of said walls having an extension which forms the portion of the casing adjacent which the impeller runs and another of said walls having an axially extending portion having mounting lugs attached thereto, said mounting lugs having mounting surfaces accurately dimensioned with respect to said wall extension, and walls which form a discharge scroll attached to said first named walls.

3. A fabricated welded compressor casing structure comprising a cone-shaped section which defines an inlet, an impeller vane wall, and a difluser side wall, a second diffuser side wall, diffuser vanes welded, between said diffuser side walls, a second cone-shaped section welded to said second diffuser side wall, attaching lugs welded to said second cone-shaped. section, said lugs having finished surfaces dimensioned with respect to said impeller vane wall, and front and rear scroll sections attached to'said cone-sections.

4. In a supercharger, the combination with a bearing housing having spaced supporting arms, a shaft, and an impeller fixed on said shaft, of a fabricated compressor casing comprising a plurality of wall sections welded together to provide a rigid structure which defines an inlet, an impeller wall adjacent to one side of the impeller and a wall extending axially with respect to said impeller wall, lugs permanently fixed to said axially extending wall provided with finished surfaces dimensioned with respect to the inner surface of'said impeller wall, detachable means fastening said lugs to said spaced supporting arms, and front and rear scroll sections attached to said rigid structure.

.5. In a supercharger, the combination with a bearing housing .having spaced supporting arms, a shaft, and an impeller fixed on said shaft, of a fabricated compressor casing comprising a plurality of wall sections welded together to provide a rigid structure which defines an inlet, an impeller wall adjacent to one side of the impeller and a. wall extending axially with respect to said impeller wall, lugs permanently fixed to said axially extending wall provided with finished surfaces dimensioned with respect to the inner surface of said impeller wall, detachable means fastening said lugs to thebearing housing, front and rear scroll sections attached to said rigid structure, and supporting means for the supercharger comprising ears attached to the peripheral portion of the scroll section and reinforcing ribs between said ears and lugs.

6. A fabricated welded compressor casing a shaft, and an impeller fixed on said shaft, of a fabricated compressor casing comprising a plurality of wall sections welded together to provide a rigid structure which defines an inlet, an impeller wall adjacent to one side of the impeller and a wall extending axially with respect to said impeller wall having a diameter greater than the impeller diameter, lugs welded to said axially extending wall having finished mounting surfaces spaced with respect to the inner surface of said impeller wall, bolts fastening said lugs to said spaced supporting arms, and front and rear scroll sections attached to said rigid structure.

8. In a compressor having a bearing housing, a shaft, and an impeller overhung on an end of the shaft, a fabricated compressor casing structure comprising a plurality of pressed metal parts united by fused metal to form an'inlet, a wall adjacent to which the impeller runs, a diffuser which surrounds the impeller, an axially extending annular wall of a diameter larger than the impeller, and walls which define a discharge scroll, said structure being positioned around the impeller by passing the impeller through said axially extending wall, means for attaching said structure to the bearing housing, and a plate carried by the bearing housing for closing the opening through said axially extending wall. v

9. In a centrifugal compressor, the combination with a shaft, an impeller on the shaft, a

- bearing for the shaft, and supporting members structure comprising a plurality of walls of heavier pressed meta] united by fused metal to form a rigid structure which provides a diffuser, a wall adjacent to which the compressor impeller runs and spaced mounting lugs having supporting surfaces accurately dimensioned with respect to the inner surface of the wall adjacent to which th impeller rims, and a plurality of walls of lighter pressed metal attached to said rigid structure to define a discharge scroll.

I. In a supercharger, the combination with a bearing housing having spaced supp rting arms.

on bearing, of a fabricated compressor casing having a plurality of walls united by fuser metal to provide a rigid structure comprising spaced walls which define a diffuser surrounding the impeller, a wall adjacent to which the impeller runs and an axially extending wall having mounting lugs provided with surfaces accurately spaced from the inner surface of the wall adjacent to which the impeller runs, means detachably connecting said surfaces to said supporting members, and walls forming a discharge scroll connected to said rigid structure.

10. In a supercharger, the combination with a bearing housing, a shaft and an impeller fixed on said shaft, of a fabricated compressor'casing comprising a plurality of wall sections welded together to provide a rigid structure which defines an inlet, an impeller wall adjacent to one side of the impeller and a wall extending axially with respect to said impeller wall having a diameter greater than the. impeller diameter, lugs carried by said axially extending wall having finished mounting surfaces accurately spaced with respect to the inner surface of said impeller wall, means fastening said lugs to the bearing housing, and walls defining a scroll attached t said rigid structure.

HOWARD A. JOHNSON. 

